I will take your oversimplifications as comedy and not as serious arguments. :lengua:
That said I will give you my opinion anyway because I know you have used some of the media you're criticising so I think you do believe some of this and it would be nice to have some exchange of opinions on how we see SN, specially Google plus.
Facebook: your mom likes your status, because you know your mom is on facebook, so you can't post anything real there.
Facebook have lists and 3 sets of trust (acquaintance, friend, close friend) so you can really have your family and still have two groups see a different side as you need.
Twitter: Unless you're a comedian, you're going to fall into one of the three categories of useless tweeters: the vapid, the incendiary, and the guy who literally just links to his own youtube videos.
Ouch. The YT-er one I have seen it often, hahah.
I opened my twitter for my community roczuz so I was a lame cyborg account of automated tweets mixed with a few authentic now and there. Now I use it a bit more but I am never constant enough to make any presence. I know taht people taht find me and add me in general are mostly looking for follow backs.
Instagram: Unless you're a photographer or some shit, nobody actually takes enough interesting pictures to maintain a presence. So you're probably posting selfies, pictures of your pets, pictures of your food, or you're a pedant wannabe photographer who takes pictures of the stop sign outside your house with a black and white filter on.
That's a point. I think whatever you post on instagram you could post in any other SN anyway.
tumblr: Nobody actually puts anything on tumblr. They just reblog things that were already on tumblr. Also, it's shockingly difficult to have a meaningful conversation on Tumblr, since you can't message people back and forth. All you can do is reblog things with a comment. Also, obligatory bitching about SJWs.
Reblogging with comment seems to be a good way to have a threaded conversation so I never really minded it. The problem with tumblr is for me the vulnerability. Whatever you post anyone can see, get offended and reblog with their own twist. It'd be nice to be able to have groups. I have a tumblr and I am one of those users taht instead of contributing sometime new I mostly do reblogs. I was hoping to sue it for my stuff but quite frankly I feel once again 'vulnerable' there. i don't trust the platform with my creations.
Now the main point Google Plus:
Google+: PEOPLE ACTUALLY TALKING ABOUT SHIT. Like, for really real. It's basically just a web forum like this one, updated for the age of social networks. With circles you can control who gets to see your content, and with collections you can separate your content into groups for people to either follow, or not.
Here's the big downside, and the reason everybody thinks google+ is a ghost town: you've gotta actually have something to talk about. If you're just a vapid 20-something who wants to rack up the Internet Points for posting pictures of "feeling sexy today," then you're not going to find a bunch of other vapid 20-somethings to talk to. BUT, if you're the kind of interesting person who actually has a passion in life, you can find people to have a conversation with about that passion.
I think it depends on the people you follow, honestly. I joined Zelda groups and they are these polls and facebook style posts. So I don't really think they stopped just because they have to think about it. I do concede that it is way easier to convey long rants on G+ than in facebook as notes are kind of a side thing taht no one really cares for and the interface of facebook does favour short posts with some media, however while G+ doesn't do this doesn't mean they discourage it. Maybe it is because as a zelda webmaster I have in my circles people generally younger than me being the ones active.
In all honestly I think Google plus is a pretty cool social network but Google annoyed people by changing the YT interface by forcing people uninterested in the G+ part to make an account. That was a very bad start. The layout too gets sometime to get used to it so there is resistance from people who won't give it much of a chance.
I don't like Facebook itself but the one click login through an account is the main reason I have an account. Facebook was good in the beginning but they have been taking off options and it has become more openly geared towards business. It is no longer about connecting with people it is about using peer pressure to persuade you toward certain brands and opinions. Yet people get picky about alternatives. So far G+ seem less direct in their commercial side, so you can actually have the people being the main point rather than if they liked X product or something.
So yeah, we might differing in our reasoning but I agree G+ is the best one of the ones you mentioned. It could do with more support.